1. Field of the Invention
The invention relates to a semiconductor device and a method of manufacturing the same, particularly, a structure of a high voltage MOS transistor and a method of manufacturing the same.
2. Description of the Related Art
A high voltage MOS transistor has a high source/drain breakdown voltage or a high gate breakdown voltage and is generally used for various drivers such as an LCD driver, a power supply circuit or the like. In recent years, there has been a need for a high voltage transistor having a high source/drain breakdown voltage and a high gate breakdown voltage together. For this purpose, a LOCOS (local oxidation of silicon) film that is basically used as a field insulation film is used as a gate insulation film to enhance the gate breakdown voltage, and at the same time a low concentration drain layer is provided to enhance the source/drain breakdown voltage. The high voltage MOS transistor is disclosed in Japanese Patent Application No. 2004-39774.